package java_cup;

import java_cup.assoc;
import java.util.Hashtable;
import java.util.Enumeration;

/**
 * This class represents a terminal symbol in the grammar. Each terminal has a
 * textual name, an index, and a string which indicates the type of object it
 * will be implemented with at runtime (i.e. the class of object that will be
 * returned by the scanner and pushed on the parse stack to represent it).
 * 
 * @version last updated: 7/3/96
 * @author Frank Flannery
 */
public class terminal extends symbol {

	/*-----------------------------------------------------------*/
	/*--- Constructor(s) ----------------------------------------*/
	/*-----------------------------------------------------------*/

	/**
	 * Full constructor.
	 * 
	 * @param nm
	 *            the name of the terminal.
	 * @param tp
	 *            the type of the terminal.
	 */
	public terminal(String nm, String tp, int precedence_side,
			int precedence_num) {
		/* superclass does most of the work */
		super(nm, tp);

		/* add to set of all terminals and check for duplicates */
		Object conflict = _all.put(nm, this);
		if (conflict != null)
			// can't throw an execption here because this is used in static
			// initializers, so we do a crash instead
			// was:
			// throw new internal_error("Duplicate terminal (" + nm +
			// ") created");
			(new internal_error("Duplicate terminal (" + nm + ") created"))
					.crash();

		/* assign a unique index */
		_index = next_index++;

		/* set the precedence */
		_precedence_num = precedence_num;
		_precedence_side = precedence_side;

		/* add to by_index set */
		_all_by_index.put(new Integer(_index), this);
	}

	/* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . */

	/**
	 * Constructor for non-precedented terminal
	 */

	public terminal(String nm, String tp) {
		this(nm, tp, assoc.no_prec, -1);
	}

	/* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . */

	/**
	 * Constructor with default type.
	 * 
	 * @param nm
	 *            the name of the terminal.
	 */
	public terminal(String nm) {
		this(nm, null);
	}

	/*-----------------------------------------------------------*/
	/*-------------------  Class Variables  ---------------------*/
	/*-----------------------------------------------------------*/

	private int _precedence_num;
	private int _precedence_side;

	/*-----------------------------------------------------------*/
	/*--- (Access to) Static (Class) Variables ------------------*/
	/*-----------------------------------------------------------*/

	/**
	 * Table of all terminals. Elements are stored using name strings as the key
	 */
	protected static Hashtable _all = new Hashtable();

	/** Access to all terminals. */
	public static Enumeration all() {
		return _all.elements();
	}

	/** Lookup a terminal by name string. */
	public static terminal find(String with_name) {
		if (with_name == null)
			return null;
		else
			return (terminal) _all.get(with_name);
	}

	/* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . */

	/** Table of all terminals indexed by their index number. */
	protected static Hashtable _all_by_index = new Hashtable();

	/** Lookup a terminal by index. */
	public static terminal find(int indx) {
		Integer the_indx = new Integer(indx);

		return (terminal) _all_by_index.get(the_indx);
	}

	/* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . */

	/** Total number of terminals. */
	public static int number() {
		return _all.size();
	}

	/* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . */

	/** Static counter to assign unique index. */
	protected static int next_index = 0;

	/* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . */

	/** Special terminal for end of input. */
	public static final terminal EOF = new terminal("EOF");

	/* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . */

	/** special terminal used for error recovery */
	public static final terminal error = new terminal("error");

	/*-----------------------------------------------------------*/
	/*--- General Methods ---------------------------------------*/
	/*-----------------------------------------------------------*/

	/** Report this symbol as not being a non-terminal. */
	@Override
	public boolean is_non_term() {
		return false;
	}

	/* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . */

	/** Convert to a string. */
	@Override
	public String toString() {
		return super.toString() + "[" + index() + "]";
	}

	/* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . */

	/** get the precedence of a terminal */
	public int precedence_num() {
		return _precedence_num;
	}

	public int precedence_side() {
		return _precedence_side;
	}

	/** set the precedence of a terminal */
	public void set_precedence(int p, int new_prec) {
		_precedence_side = p;
		_precedence_num = new_prec;
	}

	/*-----------------------------------------------------------*/

}
